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Digital Camera Patent Abstract
A digital camera module (100) and a lens (20) used therein, the
digital camera module includes a holder (10), an image pickup module
(30) and a lens (20). The holder has a window (12) defined on a
sidewall, the window is configured for receiving light. The image
pickup module includes a base (31) and a chip (33) attached to the
base, the base is mounted to the holder to cooperatively form a
receiving space therebetween. The prism lens is received in the
receiving space and formed from a first transmitting surface (22)
configured for transmitting light passing through the window, a
second reflecting surface (24) configured for reflecting light transmitted
from the first surface, and a third transmitting surface (26) configured
for transmitting the reflected light to form an image on the chip.
Digital Camera Patent Claims
1. A digital camera module, comprising: a holder, the holder having
a window defined in a sidewall, the window configured for receiving
light; an image pickup module, the image pickup module comprising
a base and a chip attached to the base, the base being mounted to
the holder, the base and the holder cooperatively forming a receiving
space therebetween; a prism lens, which is received in the receiving
space and has a first transmitting surface configured for transmitting
light passing through the window, a second reflecting surface configured
for reflecting light transmitted from the first surface, and a third
transmitting surface configured for transmitting the reflected light
to form an image on the chip.
2. The digital camera module as claimed in claim 1, wherein the
first surface, the second surface and the third surface of the lens
are described by the following matrices equations: ( X 3 .alpha.
3 .times. X ) = ( 1 0 n - n 0 - nR 3 .times. X n n 0 ) .times. (
1 d 2 0 1 ) .times. ( 1 0 - 2 R 2 .times. X 1 ) .times. ( 1 d 1
0 1 ) .times. ( 1 0 n 0 - n - nR 1 .times. X n n 0 ) .times. ( X
IMP .alpha. IMPX ) = ( 1 d 3 0 1 ) .times. ( X 3 .alpha. 3 .times.
X ) where, n.sub.0 is the refractive index in free space; n is the
refractive index in the lens; X.sub.1 is an object height on the
first surface; X.sub.3 is an object height on the second surface;
X.sub.IMP is an object height on an image plane of the lens; .alpha..sub.1X
is an incident angle between light and a line normal to the first
surface; .alpha..sub.3X is an incident angle between light and a
line normal to the third surface; .alpha..sub.IMPX is an incident
angle between light and a line normal to the image plane of the
lens; R.sub.1X is the curvature radius of the first surface; R.sub.2X
is the curvature radius of the second surface; R.sub.3X is the curvature
radius of the third surface; d.sub.1 is the distance between an
optical center of the first surface and an optical center of the
second surface; d.sub.2 is the distance between the optical center
of the second surface and an optical center of third surface; and
d.sub.3 is the distance between the optical center of the third
surface and the image plane of the lens.
3. The digital camera module as claimed in claim 2, wherein the
lens further comprises a fixing portion where the periphery of the
third surface joins with the first surface and the second surface.
4. The digital camera module as claimed in claim 3, wherein the
base comprises a board portion, a frame portion extending upwardly
from the periphery of the board portion, and a cavity formed cooperatively
by the board portion and the frame portion.
5. The digital camera module as claimed in claim 4, wherein the
frame portion comprises a stepped section comprising a first step
portion and a second step portion peripherally surrounded by the
first step portion, and the fixing portion of the lens is attached
to the second step portion of the base, and the holder is mounted
to the first step portion of the base.
6. The digital camera module as claimed in claim 4, wherein the
chip is mounted to the board portion and received in the cavity.
7. The digital camera module as claimed in claim 6, wherein the
chip is provided with a plurality of metal pads thereon, thereby
transmitting image information produced by the chip.
8. The digital camera module as claimed in claim 7 wherein the
base is provided with a plurality of bonding pads on a top surface
of the board portion, and the bonding pads are contained in the
cavity.
9. The digital camera module as claimed in claim 8, wherein the
image pickup module further comprises a plurality of wires, and
the wires electrically connect the metal pads of the chip to the
bonding pads of the base.
10. The digital camera module as claimed in claim 1, wherein the
chip of the image pickup module is on an image plane of the lens.
11. The digital camera module as claimed in claim 1, wherein the
lens is made from optical plastic by injection molding.
12. A lens used in a digital camera module, comprising: a first
transmitting surface configured for transmitting light; a second
reflecting surface configured for reflecting light transmitted from
the first surface; and a third transmitting surface configured for
transmitting the reflected light to form an image; wherein the first
surface, the second surface and the third surface are described
by the following matrices equations: ( X 3 .alpha. 3 .times. X )
= ( 1 0 n - n 0 - nR 3 .times. X n n 0 ) .times. ( 1 d 2 0 1 ) .times.
( 1 0 - 2 R 2 .times. X 1 ) .times. ( 1 d 1 0 1 ) .times. ( 1 0
n 0 - n - nR 1 .times. X n n 0 ) .times. ( X IMP .alpha. IMPX )
= ( 1 d 3 0 1 ) .times. ( X 3 .alpha. 3 .times. X ) where, n.sub.0
is the refractive index in free space; n is the refractive index
in the lens; X.sub.1 is an object height on the first surface; X.sub.3
is an object height on the second surface; X.sub.IMP is an object
height on an image plane of the lens; .alpha..sub.1X is an incident
angle between light and a line normal to the first surface; .alpha..sub.3X
is an incident angle between light and a line normal to the third
surface; .alpha..sub.IMPX is an incident angle between light and
a line normal to the image plane of the lens; R.sub.1X is the curvature
radius of the first surface; R.sub.2X is the curvature radius of
the second surface; R.sub.3X is the curvature radius of the third
surface; d.sub.1 is the distance between an optical center of the
first surface and an optical center of the second surface; d.sub.2
is the distance between the optical center of the second surface
and an optical center of third surface; and d.sub.3 is the distance
between the optical center of the third surface and the image plane
of the lens.
13. A digital camera module comprising: a housing having a receiving
cavity defined therein, and a side window defined in communication
with the receiving cavity to allow entering of outside light into
the receiving cavity; an image sensor located in the receiving cavity;
and a prism lens received in the cavity and having first, second
and third lens surfaces, the prism lens being positioned in a manner
such that the first lens surface is configured for transmitting
light passing through the side window toward second lens surface,
the second lens surface is configured for reflecting the light transmitted
from the first surface toward the third lens surface, and the third
lens surface is configured for transmitting the reflected light
from the second lens surface toward the image sensor.
Digital Camera Patent Description
TECHNICAL FIELD
[0001] The present invention generally relates to digital camera
modules and lenses used therein, and more particularly to a digital
camera module and a lens used therein which has a minimal number
optical elements and good optical performance.
BACKGROUND
[0002] With the ongoing development of micro-circuitry and multimedia
technology, digital cameras are now in widespread use. High-end
portable electronic devices such as mobile phones and PDAs (Personal
Digital Assistants) are being developed to be increasingly multi-functional.
Many of these portable electronic devices are now equipped with
a digital camera. To facilitate portability, designs of such portable
electronic devices tend to be compact, slim, and light. Accordingly,
digital cameras incorporated in the portable electronic devices
have also been required to reduce in size and weight and also in
cost.
[0003] In the digital camera equipped with generally coaxial optical
systems, optical elements are arranged in the direction of the optical
axis. Therefore, there is a limit to the reduction in thickness
of the optical systems. At the same time, the number of lens elements
unavoidably increases because it is necessary to correct chromatic
aberration produced by a refracting lens used in the optical systems.
Therefore, it is difficult to reduce the cost, size and weight in
the present related art. In addition, since there are a number of
lens elements, it is difficult to accurately coaxially assemble
the lens elements of the optical system and the assembling process
is relative complex as a result.
[0004] What is needed, therefore, is an improved digital camera
module and a lens used therein which has a minimal number of optical
elements and good optical performance.
SUMMARY
[0005] In one aspect, a digital camera module is provided. The
digital camera module includes a holder, an image pickup module
and a prism lens. The holder has a window defined on a sidewall,
the window is configured for receiving light. The image pickup module
includes a base and a chip attached to the base, the base is mounted
to the holder to cooperatively form a receiving space therebetween.
The prism lens is received in the receiving space and formed from
a first transmitting surface configured for transmitting light passing
through the window, a second reflecting surface configured for reflecting
light transmitted from the first surface, and a third transmitting
surface configured for transmitting the reflected light to form
an image on the chip.
[0006] In another aspect, a lens used in the digital camera module
is provided. The lens includes a first transmitting surface configured
for transmitting light, a second reflecting surface configured for
reflecting light transmitted from the first surface, and a third
transmitting surface configured for transmitting the reflected light
to form an image. The first surface, the second surface and the
third surface are described by the following matrices equations:
( X 3 .alpha. 3 .times. X ) = ( 1 0 n - n 0 - nR 3 .times. X n n
0 ) .times. ( 1 d 2 0 1 ) .times. ( 1 0 - 2 R 2 .times. X 1 ) .times.
( 1 d 1 0 1 ) .times. ( 1 0 n 0 - n - nR 1 .times. X n n 0 ) .times.
( X IMP .alpha. IMPX ) = ( 1 d 3 0 1 ) .times. ( X 3 .alpha. 3 .times.
X ) where, n.sub.0 is the refractive index in free space; [0007]
n is the refractive index in the lens; [0008] X.sub.1 is an object
height on the first surface; [0009] X.sub.3 is an object height
on the second surface; [0010] X.sub.IMP is an object height on an
image plane of the lens; [0011] .alpha..sub.1X is an incident angle
between light and a line normal to the first surface; [0012] .alpha..sub.3X
is an incident angle between light and a line normal to the third
surface; [0013] .alpha..sub.IMPX is an incident angle between light
and a line normal to the image plane of the lens, [0014] R.sub.1X
is the curvature radius of the first surface; [0015] R.sub.2X is
the curvature radius of the second surface; [0016] R.sub.3X is the
curvature radius of the third surface; [0017] d.sub.1 is the distance
between an optical center of the first surface and an optical center
of the second surface; [0018] d.sub.2 is the distance between the
optical center of the second surface and an optical center of third
surface; and [0019] d.sub.3 is the distance between the optical
center of the third surface and the image plane of the lens.
[0020] Other advantages and novel features will become more apparent
from the following detailed description when taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Many aspects of the present digital camera module and lens
used therein can be better understood with reference to the following
drawings. The components in the drawings are not necessarily drawn
to scale, the emphasis instead being placed upon clearly illustrating
the principles of the digital camera module and lens used therein.
Moreover, in the drawings, like reference numerals designate corresponding
parts throughout the several views.
[0022] FIG. 1 is a schematic, cross-sectional view of a digital
camera module according to a preferred embodiment; and
[0023] FIG. 2 is a schematic view of a lens of the digital camera
module.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0024] Referring to FIG. 1, in a preferred embodiment, a digital
camera module 100 includes a holder 10, a lens 20 and an image pickup
module 30. The holder 10 receives the lens 20 therein, and is disposed
on the image pickup module 30.
[0025] The holder 10 is a half-opening cylinder with a closed end
and an opening end positioned opposite to the closed end. The holder
10 is made of opaque material, or material penetrable by light with
a coating impenetrable by light coated thereon. The holder 10 has
a window 12 disposed on a sidewall. The window 12 could be a through
hole, or has a transparent board 14 embedded therein to prevent
particles or dust entering into the holder 10.
[0026] The lens 20 has a triangular prism-like shape, and is formed
from a first surface 22, a second surface 24 and a third surface
26. Each of the first surface 22, the second surface 24 and the
third surface 26 may be an asymmetrical spherical surface or an
asymmetrical aspherical surface. The first surface 22 is a first
transmitting surface and is coaxial with the window 12 of the holder
10. The second surface 24 is a reflecting surface, and is configured
to include a reflecting layer (not shown) with high reflective index
coating thereon. The third surface 26 is a second transmitting surface.
Light from an object passes through the window 12 of the holder
10 and enters the lens 20 through the first surface 22. The incident
light is reflected by the second surface 24. The reflected light
exits from the lens 20 through the third surface 26 and forms an
image on an image plane (IMP). The third surface 26 further includes
a fixing portion 261 where the periphery of the third surface 26
joins with the first surface 22 and the second surface 24. The fixing
portion 261 of the third surface 26 is configured (i.e. structured
and arranged) for cooperating with the image pickup module 30.
[0027] The lens 20 is made from optical plastic by injection molding.
As regards to FIG. 2, the first surface 22, the second surface 24
and the third surface 26 of the lens 20 are described by the following
matrices equations: ( X 3 .alpha. 3 .times. X ) = ( 1 0 n - n 0
- nR 3 .times. X n n 0 ) .times. ( 1 d 2 0 1 ) .times. ( 1 0 - 2
R 2 .times. X 1 ) .times. ( 1 d 1 0 1 ) .times. ( 1 0 n 0 - n -
nR 1 .times. X n n 0 ) .times. ( X IMP .alpha. IMPX ) = ( 1 d 3
0 1 ) .times. ( X 3 .alpha. 3 .times. X ) Where: [0028] n.sub.0,
is the refractive index in free space (i.e. air); [0029] n is the
refractive index in the lens 20; [0030] X.sub.1 is an object height
on the first surface 22; [0031] X.sub.3 is an object height on the
second surface 26; [0032] .sub.XIMP is an object height on the image
plane of the lens 20; [0033] .alpha..sub.1X is an incident angle
between light and a line normal to the first surface 22; [0034]
.alpha..sub.3X is an incident angle between light and a line normal
to the third surface 26; [0035] .alpha..sub.IMPX is an incident
angle between light and a line normal to the image plane of the
lens 20; [0036] R.sub.1X is the curvature radius of the first surface
22; [0037] R.sub.2X is the curvature radius of the second surface
24; [0038] R.sub.3X is the curvature radius of the third surface
26; [0039] d.sub.1, is the distance between an optical center of
the first surface 22 and an optical center of the second surface
24; [0040] d.sub.2 is the distance between the optical center of
the second surface 24 and an optical center of third surface; [0041]
d.sub.3 is the distance between the optical center of the third
surface 26 and the image plane of the lens 20.
[0042] The image pickup module 30 is configured (e.g. structured
and arranged) to include a base 31, a chip 33 and a plurality of
wires 35. The base 31 includes a board portion 312, a frame portion
314 extending upwardly from the periphery of the board portion 312,
and a cavity 318cooperatively defined by the board portion 312 and
the frame portion 317. The board portion 312 is provided with a
plurality of bonding pads 315 and a plurality of contacts (not shown)
thereon. The bonding pads 315 are arranged on a top surface of the
board portion 312, and are contained in the cavity 318. The contacts
are set on a bottom surface defined opposite to the top surface
of the board portion 312, and are electrically connected with the
bonding pads 315 via a connecting device e.g. through holes plated
with conductive materials, conductive leads and etc. (not shown).
The frame portion 314 has a stepped section including a first step
portion 316 and a second step portion 317. The first step portion
316 surrounds the second step portion 317, and is used to engage
with the holder 10. The second step portion 317 is provided for
mating with the fixing portion 261 of the lens 20. The chip 33 is
generally an image sensor chip and the like (e.g. a photosensitive
chip), and has an active area 331 and a plurality of metal pads
333 arranged on a top surface thereof The active area 331 is configured
for transforming light image signals into electronic image signals.
The metal pads 333 are configured for transmitting image information
produced by the chip 33. The chip 33 is attached to the board portion
312 of the base 31, and is receiving in the cavity 318 of the base
31. The wires 35 are made from conductive material, and electrically
connect the bonding pads 315 of the base 31 and the metal pads 333
of the chip 33.
[0043] In assembly, adhesive is firstly applied on the second step
portion 317 of the frame portion 314 of the image pickup module
30. Then, the lens 20 is mounted on the image pickup module 30,
wherein the fixing portion 261 is adhered to the second step portion
317 and closes the cavity 318, the active area 331 of chip 33 is
coaxial with the third surface 26 of the lens 20 and is disposed
on the image plane of the lens 20. Next, adhesive is applied on
the first step portion 316. At last, the holder 10 is adhered to
the image senor module, wherein the opening end of holder 10 is
adhered to the first step portion 316, the lens 20 is received in
the holder 10, and the window 12 is positioned corresponding to
and coaxial with the first surface 22 of the lens 20.
[0044] The digital camera module 100 is designed to be compact
in size by giving a power to a reflecting second surface 24 to reduce
aberration. Accordingly, the digital camera module 100 using the
prism lens 20 with a reflecting surface allows the number of constituent
optical elements involved in aberration correction to be reduced,
making them less than an optical system using a refracting optical
element. At the same time, the digital camera module 100 using the
prism lens 20 with a reflecting surface allows the optical system
itself to be compact in size in comparison to a refracting optical
system because the optical path is folded in the digital camera
module 100. In addition, the prism lens 20, in which the positional
relationship between surfaces is fixed, only needs to control decentration
as a single unit and does not need high assembly accuracy and a
large number of man-hours for adjustment as are needed for general
optical elements.
[0045] It is to be understood that, the digital camera module 100
may further includes other lenses to further improve optical performance,
wherein the prism lens 20 is used as a relay lens to cooperatively
form an image with other lenses.
[0046] It is believed that the present embodiments and their advantages
will be understood from the foregoing description, and it will be
apparent that various changes may be made thereto without departing
from the spirit and scope of the invention or sacrificing all of
its material advantages, the examples hereinbefore described merely
being preferred or exemplary embodiments of the invention.
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